Fix rcu_assign_pointer() dynamic linking behavior
[urcu.git] / urcu-qsbr.h
1 #ifndef _URCU_QSBR_H
2 #define _URCU_QSBR_H
3
4 /*
5 * urcu-qsbr.h
6 *
7 * Userspace RCU QSBR header.
8 *
9 * LGPL-compatible code should include this header with :
10 *
11 * #define _LGPL_SOURCE
12 * #include <urcu.h>
13 *
14 * This library is free software; you can redistribute it and/or
15 * modify it under the terms of the GNU Lesser General Public
16 * License as published by the Free Software Foundation; either
17 * version 2.1 of the License, or (at your option) any later version.
18 *
19 * This library is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 * Lesser General Public License for more details.
23 *
24 * You should have received a copy of the GNU Lesser General Public
25 * License along with this library; if not, write to the Free Software
26 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 *
28 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
29 */
30
31 #include <stdlib.h>
32 #include <pthread.h>
33
34 /*
35 * Important !
36 *
37 * Each thread containing read-side critical sections must be registered
38 * with rcu_register_thread() before calling rcu_read_lock().
39 * rcu_unregister_thread() should be called before the thread exits.
40 */
41
42 #ifdef _LGPL_SOURCE
43
44 #include <urcu-qsbr-static.h>
45
46 /*
47 * Mappings for static use of the userspace RCU library.
48 * Should only be used in LGPL-compatible code.
49 */
50
51 #define rcu_dereference _rcu_dereference
52 #define rcu_read_lock _rcu_read_lock
53 #define rcu_read_unlock _rcu_read_unlock
54
55 #define rcu_quiescent_state _rcu_quiescent_state
56 #define rcu_thread_offline _rcu_thread_offline
57 #define rcu_thread_online _rcu_thread_online
58
59 #define rcu_assign_pointer _rcu_assign_pointer
60 #define rcu_cmpxchg_pointer _rcu_cmpxchg_pointer
61 #define rcu_xchg_pointer _rcu_xchg_pointer
62 #define rcu_publish_content _rcu_publish_content
63
64 #else /* !_LGPL_SOURCE */
65
66 /*
67 * library wrappers to be used by non-LGPL compatible source code.
68 */
69
70 /*
71 * QSBR read lock/unlock are guaranteed to be no-ops. Therefore, we expose them
72 * in the LGPL header for any code to use. However, the debug version is not
73 * nops and may contain sanity checks. To activate it, applications must be
74 * recompiled with -DURCU_DEBUG (even non-LGPL/GPL applications). This is the
75 * best trade-off between license/performance/code triviality and
76 * library debugging & tracing features we could come up with.
77 */
78
79 #if (!defined(BUILD_QSBR_LIB) && defined(URCU_DEBUG))
80
81 static inline void rcu_read_lock(void)
82 {
83 }
84
85 static inline void rcu_read_lock(void)
86 {
87 }
88
89 #else /* !URCU_DEBUG */
90
91 extern void rcu_read_lock(void);
92 extern void rcu_read_unlock(void);
93
94 #endif /* !URCU_DEBUG */
95
96 extern void *rcu_dereference(void *p);
97
98 extern void rcu_quiescent_state(void);
99 extern void rcu_thread_offline(void);
100 extern void rcu_thread_online(void);
101
102 extern void *rcu_assign_pointer_sym(void **p, void *v);
103
104 #define rcu_assign_pointer(p, v) \
105 rcu_assign_pointer_sym((void **)(&(p)), (v))
106
107 extern void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new);
108 #define rcu_cmpxchg_pointer(p, old, _new) \
109 rcu_cmpxchg_pointer_sym((void **)(p), (old), (_new))
110
111 extern void *rcu_xchg_pointer_sym(void **p, void *v);
112 #define rcu_xchg_pointer(p, v) \
113 rcu_xchg_pointer_sym((void **)(p), (v))
114
115 extern void *rcu_publish_content_sym(void **p, void *v);
116 #define rcu_publish_content(p, v) \
117 rcu_publish_content_sym((void **)(p), (v))
118
119 #endif /* !_LGPL_SOURCE */
120
121 extern void synchronize_rcu(void);
122
123 /*
124 * Reader thread registration.
125 */
126 extern void rcu_register_thread(void);
127 extern void rcu_unregister_thread(void);
128
129 #endif /* _URCU_QSBR_H */
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